What can I expect from a Meade ETX-70AT? (Barlow lens question)

[Dave Kowalski]

Hi all..

I recently purchased a Meade ETX-70AT and am very happy with the results for
the price. The idea was to give my 11 year old son an introduction to basic
astronomy, and it's doing just that.
I realize it's not the Hubble, and even it's limited scope (pun intended)
provides lots of "ooh-aah" factor. Even seeing the rings of Saturn as we
did, in miniscule detail, was fine.
I'd like to bump it up a slight bit without having to do the obvious thing,
get a bigger scope!
My question is regarding the 2 barlow lenses I purchased.

For example, viewing Jupiter with a 25mm last night resulted in a nice crisp
view, color bands and 4 moons visible, but a bit small.
I put in the 2x barlow, then the 25, and after focusing again, basically
the view was identical to the 25mm alone.
What exactly should a 2x Barlow do? Am I to assume that it will give me a
double size image?

I have in my inventory a:

25mm Meade
18mm wide angle
9mm Meade
5mm plossl

2x barlow, and a 3x barlow, both Meade.

The 9mm is nice by itself, and the 5 by itself seems to create a big blur no
matter how far in or out I adjust the knob....Of course, the focus knob is a
big design flaw and I am waiting for delivery on the flexible knob to make
it easier and faster to focus. Maybe I just haven't gone far enough out

Is there a Meade specific- web page that has some tips for total novices?
Thanks for any and all help,
Dave Kowalski

Here's my first moon picture, by the way...
http://www.bennettstudios.com/dk/moonie01.jpg

[Carlos Moreno]

Dave Kowalski wrote:

> My question is regarding the 2 barlow lenses I purchased.
>
> For example, viewing Jupiter with a 25mm last night resulted in a nice crisp
> view, color bands and 4 moons visible, but a bit small.
> I put in the 2x barlow, then the 25, and after focusing again, basically
> the view was identical to the 25mm alone.
> What exactly should a 2x Barlow do? Am I to assume that it will give me a
> double size image?

Yes. And I'm sure it did.

25mm eyepiece should have given you a truly minuscule image; so,
maybe, taking into account the "forgetting factor" that all of our
senses have, you thought the image was the same size. (the "forgetting
factor" means that you would have to have both images available
simultaneously, and switch from one to the other -- then you would
probably tell the difference).

I know that a factor of 2 is not a negligible, easy-to-miss
difference, but given that 25mm really gives you a tiny image, it
is conceivable.

The 2X Barlow does indeed double the magnification -- but notice
that you would achieve the same effect with a 12.5mm eyepiece!
Given that you have a 9mm eyepiece, you're better off using that
one instead of using the barlow lens (the barlow lens is typically
useful with your low f eyepieces).

Unfortunately, in your case it seems like those Barlow lenses are
almost useless -- you can only get so much magnification from that
scope (the diameter and the dispersive quality of the glass imposes
a fundamental limitation). You mention that with the 5mm eyepiece
you already see a blurry image no matter what. This is possibly
an indication that you're hitting the limits of the scope's optic;
putting a Barlow lens will not help. It only deteriorates the
image even more, since every piece of glass that you put in the
chain adds a bit more distortion to the mix.

Search (Google, maybe?) for tutorials on telescopes and viewing;
you'll find lots of interesting tips that will help you get the
most out of it, and/or decide when you're ready to jump to a
bigger scope. Maybe on Meade's page there are introductory
sections? (worth a try: htpp://www.meade.com)

Enjoy!

Carlos
--

[John Beaderstadt]

While reading in the bathroom on Thu, 29 Apr 2004 14:24:27 GMT, I saw
that "Dave Kowalski" <dav...@optonline.net> had written:

>I recently purchased a Meade ETX-70AT and am very happy with the results for

>the price. <snip>

>Is there a Meade specific- web page that has some tips for total novices?

Try this.

http://www.weasner.com/etx/menu.html

Be sure to check out the Accessory Reviews, in response to your
"bumping up" question.

--------------
Beady's Corollary to Occam's Razor: "The likeliest explanation of any phenomenon is almost always the most boring one imaginable."

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http://www.newsfeeds.com - The #1 Newsgroup Service in the World!
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[chi...@gmail.com]

hi.. i have a meade etx 70 too with MA 9 and M25 and the moon is very blurry with both.. i can see the stars and planets.. what could be the reason.. i bought a moon filter too but still no change.. newbee.. looking for some help
thanks

[StarDust]

ETX is made for portability, you could've get more aperture out of a 4" or 6" DOB for $200 or less!

[palsing]

On Tuesday, August 9, 2016 at 8:16:04 PM UTC-7, StarDust wrote:

> ETX is made for portability, you could've get more aperture out of a 4" or 6" DOB for $200 or less!

This is the first sensible thing you have ever said here... just sayin'...

[Davoud]

StarDust wrote:
> > ...

palsing replied:

> This is the first sensible thing you have ever said here... just sayin'...

SD isn't in your kill-file yet!? You are an angel of forbearance and a
glutton for punishment!

--
I agree with almost everything that you have said and almost everything that
you will say in your entire life.

usenet *at* davidillig dawt cawm

[palsing]

On Tuesday, August 9, 2016 at 8:52:32 PM UTC-7, Davoud wrote:
> StarDust wrote:
> > > ...
>
> palsing replied:
> > This is the first sensible thing you have ever said here... just sayin'...
>
> SD isn't in your kill-file yet!? You are an angel of forbearance and a
> glutton for punishment!

Yes, exactly, a glutton for punishment I am, apparently...

\Paul A

[Mike Collins]

But the advice was 12 years too late.

[StarDust]

Really? Than how come sooo many people respond to my posts?

[StarDust]

On Tuesday, August 9, 2016 at 8:52:32 PM UTC-7, Davoud wrote:

Gee, man! Looks like you're a proper little astronomer, I bet you put any one in your kill file , who don't agree with you?
Democracy your way!

[Gerald Kelleher]

Don't take it personal and you should have taken my counsel that this was going to happen. If were you foolish enough to believe that there isn't an enclave in the forum then you get what you deserve.

[StarDust]

... and who are you?

[Gerald Kelleher]

Good response but I am the guy who saw it coming a mile away and have enough heart to remind you that you are burnt flesh among these dummies.

[wsne...@hotmail.com]

On Wednesday, August 10, 2016 at 5:30:55 AM UTC-4, StarDust wrote:

> Gee, man! Looks like you're a proper little astronomer, I bet you put any one in your kill file , who don't agree with you?
> Democracy your way!

Watch out! Duh-void owns a Questar and he's not afraid to use it!

He does seem to kill-file those who disagree with him. Usually, kill-filing is for off-topic posters, such as roland or peterson.

[Chris.B]

On Wednesday, 10 August 2016 14:36:24 UTC+2, wsne...@hotmail.com wrote:
>
> He does seem to kill-file those who disagree with him. Usually, kill-filing is for off-topic posters, such as SuperRoland or Professor Peterson.

Should I be offended that you didn't mention the only sensible one here?

You seem to have been absent for a while...

Voluntary? Or was it for your own safety? ;-)

[wsne...@hotmail.com]

On Wednesday, August 10, 2016 at 10:50:19 AM UTC-4, Chris.B wrote:
> On Wednesday, 10 August 2016 14:36:24 UTC+2, wsne...@hotmail.com wrote:
> >
> > He does seem to kill-file those who disagree with him. Usually,

> >kill-filing is for off-topic posters, such as roland or peterson.

Is is poor etiquette to misquote someone, you little turd.

> Should I be offended that you didn't mention the only sensible one here?
>
> You seem to have been absent for a while...
>
> Voluntary? Or was it for your own safety? ;-)

The reason isn't actually any of your business you little piece of worthless shit. Mind you words.

[wsne...@hotmail.com]

On Wednesday, August 10, 2016 at 10:50:19 AM UTC-4, Chris.B wrote:

> You seem to have been absent for a while...
>
> Voluntary? Or was it for your own safety? ;-)

http://kellywarnerlaw.com/denmark-defamation-laws/

Do not cross my path again, or make any more defamatory comments, ever again, about me, or anyone else, or anything else on this forum.

I am not in any mood to put up with your shit and I won't.

[Chris L Peterson]

It isn't voluntary. It's mandated anger management treatment forced by
the court in response to a domestic violence incident. It's a matter
of public record in Gwinnett County.

[RichA]

The ETX 70 was being blown out at the time at places like Costco for about $50.00. It was even cheap on Ebay. There is nothing wrong with the scope, it's just a small, fast achromat with a goto drive.

[wsne...@hotmail.com]

None of that is true, peterson.

[Gerald Kelleher]

Even by the low standards of this newsgroup, it is a particularly bad day.

[Mike Collins]

However this post is about advice for an 11 year old and dates from 2004.
That 11 year old is now 23 so I think your advice is a little late.

[wsne...@hotmail.com]

On Wednesday, August 10, 2016 at 1:05:47 PM UTC-4, Mike Collins wrote:

> However this post is about advice for an 11 year old and dates from 2004.
> That 11 year old is now 23 so I think your advice is a little late.

The information and discussion is still useful for others.

[StarDust]

I owned a plastic ETX 90 non-goto, back in the late 90's, got rid of it quick!
Little knobs, noisy, sounds like a coffee grinder, f/13.5 any thing I touched on the scope vibration, vibration. It had nylon gears. Scope is more frustration than useful!
I'm much more happy with my ED 80 mm f/5 refractor!

[Sketcher]

Your problem is tough to diagnose with the limited information provided. If the stars focus to tiny 'pinpoints' and the planets can be sharply focused then we can rule out focusing problems with the telescope.

Try observing the moon when its 'high' in the sky. Looking at any celestial object when low in the sky (near the horizon) is likely to result in a blurry view.

If you've only tried observing the moon when it's been full, that might give the impression of a blurry image. Try observing the moon when it's near quarter phase. Another thing to try would be observing the moon before the sky gets 'dark' - during evening or morning twilight. Doing so reduces the extreme contrast between something that's very bright (the moon) and something that's much darker (the background night sky).

Make sure your optics are clean. Sometimes a moist eyeball (or breathing) close to an eyepiece can 'fog up' the eyepiece's eye lens - resulting in a blurry view.

You could invite others to look at the moon to see if they see a sharp or a blurry moon. It could be an experience issue or a human vision issue.

You could try making a reduced aperture mask. Take a piece of cardboard (perhaps from a cereal box, etc.) and cut a 50mm hole in it. Center the mask over the front of the telescope and see if that helps.

Verify that the telescope is pointed directly at the moon and you're not looking at glare from a nearby moon that's just outside the telescope's field of view.

If you think of other things to try - go for it! Sometimes we have to experiment and try different things.

Sketcher

[Bill]

Thank you Sketcher!

20+ posts inthis thread, and yours was the only attempt I saw which was
attempting to help the poster with their problem.

--
Email address is a Spam trap.

[StarDust]

... or just sell it on ebay for parts and buy a new that works! LOL!

[wsne...@hotmail.com]

On Tuesday, August 9, 2016 at 10:34:15 PM UTC-4, chi...@gmail.com wrote:
> hi.. i have a meade etx 70 too with MA 9 and M25 and the moon is very blurry >with both.. i can see the stars and planets.. what could be the reason.. i >bought a moon filter too but still no change.. newbee.. looking for some help
> thanks

This is an f/5 achromatic refractor, probably not the best choice for high magnification due to its chromatic aberration. It should be fine for low or even medium powers. It is slightly smaller than my finder scope and about the same mag with a 25mm eyepiece.

A 70mm refractor of f/10 or slightly longer should give better images. Better still would be 6- or 8-inch Dobsonian of moderate focal length. That would gather more light, be free of chromatic aberration, have good ergonomics and be an affordable choice if you are really interested in astronomy.

As far as why the Moon looks blurry, you could have dirty optics, misplaced or missing baffles, hazy sky conditions, a main lens or an eyepiece that was taken apart and poorly re-assembled, vision problems, etc.

[StarDust]

f/5 refractor, achromate, I think he has to spend some money on good quality eyepieces. At f/10 or f/15 refractor is very forgiving , cheap eyepieces can be used, like those old Kernels.

[wsne...@hotmail.com]

On Wednesday, August 10, 2016 at 7:35:24 PM UTC-4, StarDust wrote:

> f/5 refractor, achromate, I think he has to spend some money on good quality eyepieces. At f/10 or f/15 refractor is very forgiving , cheap eyepieces can be used, like those old Kernels.

Better eyepieces would help, but a bigger, better telescope would help more, and might actually include some better eyepieces. Meanwhile, he can try to use his existing telescope as is.

[StarDust]

As they say- You get what you payed for!

[wsne...@hotmail.com]

And he has a telescope that should be able to provide fine wide angle views, and much more.

[Mike Collins]

The telescope should be able to give a clear image of the moon with any
crap eyepiece . He need to find his nearest astronomy club and ask their
advice. Either the scope is broken or he's using it wrong.

[wsne...@hotmail.com]

There could also be uncorrected vision problems. Or maybe there is no problem in the first place.

[StarDust]

On Thursday, August 11, 2016 at 9:21:45 AM UTC-7,> On Thursday, August 11, 2016 at 11:56:07 AM UTC-4, Mike Collins wrote:
> > wrote:
> > > On Wednesday, August 10, 2016 at 7:35:24 PM UTC-4, StarDust wrote:
> > >
> > >> f/5 refractor, achromate, I think he has to spend some money on good
> > >> quality eyepieces. At f/10 or f/15 refractor is very forgiving , cheap
> > >> eyepieces can be used, like those old Kernels.
> > >
> > > Better eyepieces would help, but a bigger, better telescope would help
> > > more, and might actually include some better eyepieces. Meanwhile, he
> > > can try to use his existing telescope as is.
> > >
> >
> > The telescope should be able to give a clear image of the moon with any
> > crap eyepiece . He need to find his nearest astronomy club and ask their
> > advice. Either the scope is broken or he's using it wrong.
>
> There could also be uncorrected vision problems. Or maybe there is no problem in the first place.

Maybe he forgot to put his glasses on? LOL!

[wsne...@hotmail.com]

Maybe he has really bad astigmatism?

[StarDust]

What ever, sell it for parts on Ebay, get a new ETX throw away plastic scope!
I think, these 70 mm ETX's sell for less than $100 on ebay!
10-15 years ago were all the uhh-ahh about them!

[Ancelot]

70mm is good but not enough for astrophoto. I have a Meade EXT-70AT and a Celestron 114EQ.

[wsne...@hotmail.com]

I was suggesting that the astigmatism was in his eyes, not his telescope.

[StarDust]

He would know that, even by looking at hot girls?

[wsne...@hotmail.com]

Assuming that he is even still reading this thread, perhaps he might try including his glasses in the optical train.

[RichA]

Meade made it to a price point. But the optics in the OTA were close to Questar and very consistent across the line.

[StarDust]

Maks are easy to make, spherical optics, very simple, but long f ratio.
Larger ones get heavy!

[Chris.B]

On Thursday, 11 August 2016 21:46:29 UTC+2, StarDust wrote:
>
> He would know that, even by looking at hot girls?

Wouldn't they be "upside down" in an astronomical telescope?
Perhaps that's part of their charm?

[wsne...@hotmail.com]

On Friday, August 12, 2016 at 12:02:24 AM UTC-4, StarDust wrote:

> Maks are easy to make, spherical optics, very simple, but long f ratio.
> Larger ones get heavy!

Almost all Maks are small, however, and in those small apertures, even Newtonians and most refractors are of a manageable size and with more moderate, more versatile focal ratios, for most astronomical use.

That said, the current C90 seems like a good deal, especially if one already owns a suitable mount to use with it.

[Mike Collins]

Not in an ETX. They give an upright mirror image.

[Chris.B]

That doesn't sound very sensible.
This can't be easily corrected using familiar components.[Star or 45° diagonal]
Just imagine Stardust's Standard T-shirt Text Intelligibility Paradox:

!sniarb erew eseht hsiw I

;-)

[StarDust]

That's mirror image, my buffalo breath friend!
But after a few cups of cheap Vodka, every thing looks upside down!

[Chris.B]

On Saturday, 13 August 2016 17:48:58 UTC+2, StarDust wrote:
>
> That's mirror image, my buffalo breath friend!
> But after a few cups of cheap Vodka, every thing looks upside down!

An alcoholic inversion?

I've seen liquid filled prisms but there was no mention of alcohol having such magical powers. ;-)

BTW: Why buffalo breath? Is this a local colloquialism?

[StarDust]

On Sunday, August 14, 2016 at 1:59:49 AM UTC-7, Chris.B wrote:
> On Saturday, 13 August 2016 17:48:58 UTC+2, StarDust wrote:
> >
> > That's mirror image, my buffalo breath friend!
> > But after a few cups of cheap Vodka, every thing looks upside down!
>
> An alcoholic inversion?
>
> I've seen liquid filled prisms but there was no mention of alcohol having such magical powers. ;-)

Yes, specially drank on empty stomach! LOL!